Tuesday, June 16, 2009

Assemblies provide a way to package modules containing MSIL and metadata into units for deployment. The goal of writing code is not to package and deploy it, however; it's to run it. The final section of this chapter looks at the most important aspects of running managed code.Assemblies are loaded into memory only when needed

Loading AssembliesWhen an application built using the .NET Framework is executed, the assemblies that make up that application must be found and loaded into memory. Assemblies aren't loaded until they're needed, so if an application never calls any methods in a particular assembly, that assembly won't be loaded. (In fact, it need not even be present on the machine where the application is running.) Before any code in an assembly can be loaded, however, it must be found. How is this done?

The answer is not simple. In fact, the process the CLR uses to find assemblies is too complex to describe completely here. The broad outlines of the process are fairly straightforward, however. First, the CLR determines what version of a particular assembly it's looking for. By default, it will look only for the exact version specified for this assembly in the manifest of the assembly from which the call originated. This default can be changed by settings in various configuration files, so the CLR examines these files before it commences its search.

The CLR follows well-defined but involved rules to locate an assemblyOnce it has determined exactly which version it needs, the CLR checks whether the desired assembly is already loaded. If it is, the search is over; this loaded version will be used. If the desired assembly is not already loaded, the CLR will begin searching in various places to find it. The first place the CLR looks is usually the global assembly cache (GAC), a special directory intended to hold assemblies that are used by more than one application. Installing assemblies in this global assembly cache requires a process slightly more complex than just copying the assembly, and the cache can contain only assemblies with strong names.

The CLR looks first in the global assembly cacheIf the assembly it's hunting for isn't in the global assembly cache, the CLR continues its search by checking for a codebase element in one of the configuration files for this application. If one is found, the CLR looks in the location this element specifies, such as a directory, for the desired assembly. Finding the right assembly in this location means the search is over, and this assembly will be loaded and used. Even if the location pointed to by a codebase element does not contain the desired assembly, however, the search is nevertheless over. A codebase element is meant to specify exactly where the assembly can be found. If the assembly is not at that location, something has gone wrong, the CLR gives up, and the attempt to load the new assembly fails.

The CLR can next look in the location referenced by a codebase elementIf there is no codebase element, however, the CLR will begin its last-ditch search for the desired assembly, a process called probing, in what's known as the application base. This can be either the root directory in which the application is installed or a URL, perhaps on some other machine. (It's worth pointing out that the CLR does not assume that all necessary assemblies for an application are installed on the same machine; they can also be located and installed across an internal network or the Internet.) If the elusive assembly isn't found here, the CLR continues searching in several other directories based on the name of the assembly, its culture, and more.

If no codebase element exists, the CLR searches in other places

Despite the apparent complexity of this process, this description is not complete. There are other alternatives and even more options. For developers working with the .NET Framework, it's probably worth spending some time understanding this process in detail. Putting in the effort up front is likely to save time later when applications don't behave as expected.

Compiling MSILA compiler that produces managed code always generates MSIL. Yet MSIL can't be executed by any real processor. Before it can be run, MSIL code must be compiled yet again into native code that targets the processor on which it will execute. Two options exist for doing this: MSIL code can be compiled one method at a time during execution, or it can be compiled into native code all at once before an assembly is executed. This section describes both of these approaches.

JIT CompilationThe most common way to compile MSIL into native code is to let the CLR load an assembly and then compile each method the first time that method is invoked. Because each method is compiled only when it's first called, the process is called just-in-time (JIT) compilation.MSIL code is typically JIT compiled before it's executed

The first time that an Asp.Net web form page is executed, the code contained with the page (any codebehind class module associated with the page ) is complied into a class that inherits from the Page base class ( actually, the code-behing class inherits from the Page class and then the .aspx file inherits from code-behind class via the Inherits attributes of the @ Page directive ).

The following illustration show the relationship between the Page, its code-behind class (if any) and the complied assembly. Once complied, the class is executed, the resulting Html is rendered to the browser, and the class removed from hte memory.

Web services are stored on server and delivered to user over internet. A web application is usually a three- tier sturcture, comprising a User Services Tier (allowing user to access application), a Business Service tier(allowing user to carry out complex activites) and Data Services tier (which allows data storage and ritrival)

# System.Reflaction namespace contain classes that can be used to introgate the types for module/ assemly.

# All .NeT compliers produce metadata about the types defined in the modules they produce. This metadata is package along with the module (modules in the terms are packaged together assemblies) can be accessed by the machinism called reflection.

# You can use reflaction to dynamically create an instance of a type , bind the type to an existing object, or get the type from an existing object.

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Q1. Explain the differences between Server-side and Client-side code? Ans. Server side code will execute at server (where the website is hosted) end, & all the business logic will execute at server end where as client side code will execute at client side (usually written in javascript, vbscript, jscript) at browser end.

Q2. What type of code (server or client) is found in a Code-Behind class? Ans. Server side code.

Q3. How to make sure that value is entered in an asp:Textbox control?Ans. Use a RequiredFieldValidator control.

Q4. Which property of a validation control is used to associate it with a server control on that page?Ans. ControlToValidate property. Q5. How would you implement inheritance using VB.NET & C#? Ans. C# Derived Class : Baseclass VB.NEt : Derived Class Inherits Baseclass

Q6. Which method is invoked on the DataAdapter control to load the generated dataset with data?Ans. Fill() method.

Q7. What method is used to explicitly kill a user's session? Ans. Session.Abandon()

Q8. What property within the asp:gridview control is changed to bind columns manually? Ans. Autogenerated columns is set to false Q9. Which method is used to redirect the user to another page without performing a round trip to the client? Ans. Server.Transfer method.

Q10. How do we use different versions of private assemblies in same application without re-build? Ans.Inside the Assemblyinfo.cs or Assemblyinfo.vb file, we need to specify assembly version. assembly: AssemblyVersion

Q11. Is it possible to debug java-script in .NET IDE? If yes, how? Ans. Yes, simply write "debugger" statement at the point where the breakpoint needs to be set within the javascript code and also enable javascript debugging in the browser property settings.

Q12. How many ways can we maintain the state of a page? Ans. 1. Client Side - Query string, hidden variables, viewstate, cookies2. Server side - application , cache, context, session, database

Q13. What is the use of a multicast delegate? Ans. A multicast delegate may be used to call more than one method.

Q14. What is the use of a private constructor? Ans. A private constructor may be used to prevent the creation of an instance for a class.

Q15. What is the use of Singleton pattern? Ans. A Singleton pattern .is used to make sure that only one instance of a class exists.

Q16. When do we use a DOM parser and when do we use a SAX parser?Ans. The DOM Approach is useful for small documents in which the program needs to process a large portion of the document whereas the SAX approach is useful for large documents in which the program only needs to process a small portion of the document.

Q17. Will the finally block be executed if an exception has not occurred?Ans.Yes it will execute.

Q18. What is a Dataset?Ans. A dataset is an in memory database kindof object that can hold database information in a disconnected environment.

Q19. Is XML a case-sensitive markup language? Ans. Yes.

Q20. What is an .ashx file?Ans. It is a web handler file that produces output to be consumed by an xml consumer client (rather than a browser).

Q21. What is encapsulation?Ans. Encapsulation is the OOPs concept of binding the attributes and behaviors in a class, hiding the implementation of the class and exposing the functionality.

Q22. What is Overloading?Ans. When we add a new method with the same name in a same/derived class but with different number/types of parameters, the concept is called overluoad and this ultimately implements Polymorphism.

Q23. What is Overriding?Ans. When we need to provide different implementation in a child class than the one provided by base class, we define the same method with same signatures in the child class and this is called overriding.

Q24. What is a Delegate? Ans. A delegate is a strongly typed function pointer object that encapsulates a reference to a method, and so the function that needs to be invoked may be called at runtime.

Q25. Is String a Reference Type or Value Type in .NET? Ans. String is a Reference Type object.

Q26. What is a Satellite Assembly? Ans. Satellite assemblies contain resource files corresponding to a locale (Culture + Language) and these assemblies are used in deploying an application globally for different languages.

Q27. What are the different types of assemblies and what is their use?Ans. Private, Public(also called shared) and Satellite Assemblies.

Q28. Are MSIL and CIL the same thing?Ans. Yes, CIL is the new name for MSIL.

Q29. What is the base class of all web forms?Ans. System.Web.UI.Page

Q30. How to add a client side event to a server control?Ans. Example... BtnSubmit.Attributes.Add("onclick","javascript:fnSomeFunctionInJavascript()");

Q31. How to register a client side script from code-behind?Ans. Use the Page.RegisterClientScriptBlock method in the server side code to register the script that may be built using a StringBuilder.

Q32. Can a single .NET DLL contain multiple classes?Ans. Yes, a single .NET DLL may contain any number of classes within it.

Q33. What is DLL Hell?Ans. DLL Hell is the name given to the problem of old unmanaged DLL's due to which there was a possibility of version conflict among the DLLs.

Q34. can we put a break statement in a finally block?Ans. The finally block cannot have the break, continue, return and goto statements.

Q35. What is a CompositeControl in .NET?Ans. CompositeControl is an abstract class in .NET that is inherited by those web controls that contain child controls within them.

Q36. Which control in asp.net is used to display data from an xml file and then displayed using XSLT?Ans. Use the asp:Xml control and set its DocumentSource property for associating an xml file, and set its TransformSource property to set the xml control's xsl file for the XSLT transformation.

Q37. Can we run ASP.NET 1.1 application and ASP.NET 2.0 application on the same computer?Ans. Yes, though changes in the IIS in the properties for the site have to be made during deployment of each.

Q38. What are the new features in .NET 2.0? Ans. Plenty of new controls, Generics, anonymous methods, partial classes, iterators, property visibility (separate visibility for get and set) and static classes.

Q39. Can we pop a MessageBox in a web application?Ans. Yes, though this is done clientside using an alert, prompt or confirm or by opening a new web page that looks like a messagebox.

Q40. What is managed data?Ans. The data for which the memory management is taken care by .Net runtimeâ€™s garbage collector, and this includes tasks for allocation de-allocation.

Q41. How to instruct the garbage collector to collect unreferenced data?Ans. We may call the garbage collector to collect unreferenced data by executing the System.GC.Collect() method.

Q42. How can we set the Focus on a control in ASP.NET?Ans. txtBox123.Focus(); OR Page.SetFocus(NameOfControl);

Q43. What are Partial Classes in Asp.Net 2.0?Ans. In .NET 2.0, a class definition may be split into multiple physical files but partial classes do not make any difference to the compiler as during compile time, the compiler groups all the partial classes and treats them as a single class.

Q44. How to set the default button on a Web Form? Ans.

Q45.Can we force the garbage collector to run?Ans. Yes, using the System.GC.Collect(), the garbage collector is forced to run in case required to do so.

Q46. What is Boxing and Unboxing?Ans. Boxing is the process where any value type can be implicitly converted to a reference type object while Unboxing is the opposite of boxing process where the reference type is converted to a value type.

Q47. What is Code Access security? What is CAS in .NET?Ans. CAS is the feature of the .NET security model that determines whether an application or a piece of code is permitted to run and decide the resources it can use while running.

Q48. What is Multi-tasking?Ans. It is a feature of operating systems through which multiple programs may run on the operating system at the same time, just like a scenario where a Notepad, a Calculator and the Control Panel are open at the same time.

Q49. What is Multi-threading?Ans. When an application performs different tasks at the same time, the application is said to exhibit multithreading as several threads of a process are running.2

Q50. What is a Thread?Ans. A thread is an activity started by a process and its the basic unit to which an operating system allocates processor resources.

Q51. What does AddressOf in VB.NET operator do?Ans. The AddressOf operator is used in VB.NET to create a delegate object to a method in order to point to it.

Q52. How to refer to the current thread of a method in .NET?Ans. In order to refer to the current thread in .NET, the Thread.CurrentThread method can be used. It is a public static property.

Q53. How to pause the execution of a thread in .NET?Ans. The thread execution can be paused by invoking the Thread.Sleep(IntegerValue) method where IntegerValue is an integer that determines the milliseconds time frame for which the thread in context has to sleep.

Q54. How can we force a thread to sleep for an infinite period?Ans. Call the Thread.Interupt() method.

Q55. What is Suspend and Resume in .NET Threading?Ans. Just like a song may be paused and played using a music player, a thread may be paused using Thread.Suspend method and may be started again using the Thread.Resume method. Note that sleep method immediately forces the thread to sleep whereas the suspend method waits for the thread to be in a persistable position before pausing its activity.

Q56. How can we prevent a deadlock in .Net threading?Ans. Using methods like Monitoring, Interlocked classes, Wait handles, Event raising from between threads, using the ThreadState property.

Q57. What is Ajax?Ans. Asyncronous Javascript and XML - Ajax is a combination of client side technologies that sets up asynchronous communication between the user interface and the web server so that partial page rendering occur instead of complete page postbacks.

Q58. What is XmlHttpRequest in Ajax?Ans. It is an object in Javascript that allows the browser to communicate to a web server asynchronously without making a postback.

Q59. What are the different modes of storing an ASP.NET session?Ans. InProc (the session state is stored in the memory space of the Aspnet_wp.exe process but the session information is lost when IIS reboots), StateServer (the Session state is serialized and stored in a separate process call Viewstate is an object in .NET that automatically persists control setting values across the multiple requests for the same page and it is internally maintained as a hidden field on the web page though its hashed for security reasons.

Q60. What is a delegate in .NET?Ans. A delegate in .NET is a class that can have a reference to a method, and this class has a signature that can refer only those methods that have a signature which complies with the class.

Q61. Is a delegate a type-safe functions pointer?Ans. Yes

Q62. What is the return type of an event in .NET?Ans. There is No return type of an event in .NET.

Q63. Is it possible to specify an access specifier to an event in .NET?Ans. Yes, though they are public by default.

Q64. Is it possible to create a shared event in .NET?Ans. Yes, but shared events may only be raised by shared methods.

Q65. How to prevent overriding of a class in .NET?Ans. Use the keyword NotOverridable in VB.NET and sealed in C#.

Q66. How to prevent inheritance of a class in .NET?Ans. Use the keyword NotInheritable in VB.NET and sealed in C#.

Q67. What is the purpose of the MustInherit keyword in VB.NET?Ans. MustInherit keyword in VB.NET is used to create an abstract class.

Q68. What is the access modifier of a member function of in an Interface created in .NET?Ans. It is always public, we cant use any other modifier other than the public modifier for the member functions of an Interface.

Q69. What does the virtual keyword in C# mean?Ans. The virtual keyword signifies that the method and property may be overridden.

Q70. How to create a new unique ID for a control?Ans. ControlName.ID = "ControlName" + Guid.NewGuid().ToString(); //Make use of the Guid class

Q71A. What is a HashTable in .NET?Ans. A Hashtable is an object that implements the IDictionary interface, and can be used to store key value pairs. The key may be used as the index to access the values for that index.

Q71B. What is an ArrayList in .NET?Ans. Arraylist object is used to store a list of values in the form of a list, such that the size of the arraylist can be increased and decreased dynamically, and moreover, it may hold items of different types. Items in an arraylist may be accessed using an index.

Q72. What is the value of the first item in an Enum? 0 or 1?Ans. 0

Q73. Can we achieve operator overloading in VB.NET?Ans. Yes, it is supported in the .NET 2.0 version, the "operator" keyword is used.

Q74. What is the use of Finalize method in .NET?Ans. .NET Garbage collector performs all the clean up activity of the managed objects, and so the finalize method is usually used to free up the unmanaged objects like File objects, Windows API objects, Database connection objects, COM objects etc.

Q75. How do you save all the data in a dataset in .NET?Ans. Use the AcceptChanges method which commits all the changes made to the dataset since last time Acceptchanges was performed.

Q76. Is there a way to suppress the finalize process inside the garbage collector forcibly in .NET?Ans. Use the GC.SuppressFinalize() method.

Q77. What is the use of the dispose() method in .NET?Ans. The Dispose method in .NET belongs to IDisposable interface and it is best used to release unmanaged objects like File objects, Windows API objects, Database connection objects, COM objects etc from the memory. Its performance is better than the finalize() method.

Q78. Is it possible to have have different access modifiers on the get and set methods of a property in .NET?Ans. No we can not have different modifiers of a common property, which means that if the access modifier of a property's get method is protected, and it must be protected for the set method as well.

Q79. In .NET, is it possible for two catch blocks to be executed in one go?Ans. This is NOT possible because once the correct catch block is executed then the code flow goes to the finally block.

Q80. Is there any difference between System.String and System.StringBuilder classes?Ans. System.String is immutable by nature whereas System.StringBuilder can have a mutable string in which plenty of processes may be performed.

Q81. What technique is used to figure out that the page request is a postback?Ans. The IsPostBack property of the page object may be used to check whether the page request is a postback or not. IsPostBack property is of the type Boolean.

Q82. Which event of the ASP.NET page life cycle completely loads all the controls on the web page?Ans. The Page_load event of the ASP.NET page life cycle assures that all controls are completely loaded. Even though the controls are also accessible in Page_Init event but here, the viewstate is incomplete.

Q83. How is ViewState information persisted across postbacks in an ASP.NET webpage?Ans. Using HTML Hidden Fields, ASP.NET creates a hidden field with an ID="__VIEWSTATE" and the value of the page's viewstate is encoded (hashed) for security.

Q84. What is the ValidationSummary control in ASP.NET used for?Ans. The ValidationSummary control in ASP.NET displays summary of all the current validation errors.

Q85. What is AutoPostBack feature in ASP.NET?Ans. In case it is required for a server side control to postback when any of its event is triggered, then the AutoPostBack property of this control is set to true.

Q86. What is the difference between Web.config and Machine.Config in .NET?Ans. Web.config file is used to make the settings to a web application, whereas Machine.config file is used to make settings to all ASP.NET applications on a server(the server machine).

Q87. What is the difference between a session object and an application object?Ans. A session object can persist information between HTTP requests for a particular user, whereas an application object can be used globally for all the users.

Q88. Which control has a faster performance, Repeater or Datalist?Ans. Repeater.

Q89. Which control has a faster performance, Datagrid or Datalist?Ans. Datalist.

Q90. How to we add customized columns in a Gridview in ASP.NET?Ans. Make use of the TemplateField column.

Q91. Is it possible to stop the clientside validation of an entire page?Ans. Set Page.Validate = false;

Q92. Is it possible to disable client side script in validators?Ans. Yes. simply EnableClientScript = false.

Q93. How do we enable tracing in .NET applications?Ans.

Q94. How to kill a user session in ASP.NET?Ans. Use the Session.abandon() method.

Q95. Is it possible to perform forms authentication with cookies disabled on a browser?Ans. Yes, it is possible.

Q96. What are the steps to use a checkbox in a gridview?Ans.OnCheckedChanged="Check_Clicked">

Q97. What are design patterns in .NET?Ans. A Design pattern is a repeatitive solution to a repeatitive problem in the design of a software architecture.

Q98. What is difference between dataset and datareader in ADO.NET?Ans. A DataReader provides a forward-only and read-only access to data, while the DataSet object can carry more than one table and at the same time hold the relationships between the tables. Also note that a DataReader is used in a connected architecture whereas a Dataset is used in a disconnected architecture.

Q99. Can connection strings be stored in web.config?Ans. Yes, in fact this is the best place to store the connection string information.

Q100. Whats the difference between web.config and app.config?Ans. Web.config is used for web based asp.net applications whereas app.config is used for windows based applications.

Que. What is the access modifier of a member function of in an Interface created in .NET?Ans. It is always public, we cant use any other modifier other than the public modifier for the member functions of an Interface.

Que. What is the difference between a session object and an application object?Ans. A session object can persist information between HTTP requests for a particular user, whereas an application object can be used globally for all the users.

Que. What are the new features in .NET 2.0? Ans. Plenty of new controls, Generics, anonymous methods, partial classes, iterators, property visibility (separate visibility for get and set) and static classes.

IDLDPL systems are fully integrated solutions, developed on 3 tier architecture. They provide a backbone foundation system that provides most of the day-to-day business transactions. They are designed to deliver a seamless integration of information and knowledge. These systems are very powerful tools that can provide significant benefit to any distributed departments.In addition, these fully integrated systems establish a foundation platform for delivering Web-based services and transactions, providing additional value to the organization and its customers.

IDLDPL contains the following modules:-?

Masters – First interface for add Employer, Customer, Supplier, Products etc as well as all the dropdown down values like Bank name, Brand Name etc.

Sale – Generate Order Form, Order Purchasing Form, and Invoice all with Edit, View Copy and Detail Facilities.

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